Electro-photographic 3-D printing using collapsible substrate

ABSTRACT

In 3-D printing a platen moves toward an intermediate transfer belt (ITB) to have a sheet positioned on the platen contact the ITB to electrostatically transfer a layer of different materials to the sheet, and then the platen moves to a stabilization station to join the layer to the sheet. This processing is repeated to have the sheet repeatedly contact the ITB (with intervening stabilization at the stabilization station) to successively form layers of the materials on the sheet. The freestanding stack is fed to a platform to successively form a 3-D structure of freestanding stacks of the layers. Heat and/or pressure and/or light are applied to the 3-D structure to bond the freestanding stacks to one another through the sheets of collapsible media on the platform.

BACKGROUND

Systems and methods herein generally relate to three-dimensional (3-D)printing processes that use electrostatic printing processes.

Three-dimensional printing can produce objects using, for example,ink-jet or electrostatic printers. In one exemplary three-stage process,a pulverulent material is printed in thin layers, a UV-curable liquid isprinted on the pulverulent material, and finally each layer is hardenedusing a UV light source. These steps are repeated layer-by-layer.Support materials generally comprise acid-, base- or water-solublepolymers, which can be selectively rinsed from the build material after3-D printing is complete.

The electrostatic (electro-photographic) process is a well-known meansof generating two-dimensional digital images that transfer materialsonto an intermediate surface (such as a photoreceptor belt or drum).Advancements in the way an electro-photographic image is transferred canleverage the speed, efficiency and digital nature of printing systems.

SUMMARY

Exemplary three-dimensional (3-D) printers include, among othercomponents, an intermediate transfer belt (ITB), a first photoreceptorpositioned to electrostatically transfer a first material to the ITB,and a second photoreceptor positioned to electrostatically transfer asecond material to a location of the ITB where the first material islocated on the ITB. The second material dissolves in different solventsrelative to solvents that dissolve the first material. Each layer of thefirst and second materials is on a discrete area of the ITB and is in apattern.

Also, a platen moves relative to the ITB, and a sheet feeder ispositioned to feed sheets of collapsible media to the platen. Thecollapsible media comprises a porous material having a densityrelatively lower than the layer of first material and second material,and can be for example a foam of polystyrene or plastic, having aporosity above 95%.

The platen moves toward the ITB to have a sheet of collapsible mediapositioned on the platen repeatedly contact the ITB. The ITB transfers alayer of the first and second materials to the sheet each time theplaten contacts the sheet of collapsible media with the ITB tosuccessively form a freestanding stack of layers of the first and secondmaterials on the sheet of collapsible media.

Also, a stabilization station is adjacent the platen. The platen canmove to the stabilization station after each time the ITB transfers eachof the layers to the sheet of collapsible media to independentlystabilize each of the layers of first and second materials.

A platform is positioned to receive, from the platen, the freestandingstack to successively form a 3-D structure of freestanding stacks of thelayers. Also, a bonding station is positioned to apply heat and/orpressure and/or light to the 3-D structure to bond the freestandingstacks to one another through said sheets of collapsible media on theplatform. More specifically, the bonding station applies the lightand/or the heat after each time the platen transfers each of thefreestanding stacks to the platform to independently bond each thefreestanding stack to any previously transferred freestanding stacksthrough the sheets of collapsible media on the platform.

The structure can also include a support material removal stationpositioned to receive the 3-D structure from the platform. The supportmaterial removal station applies a solvent that dissolves the secondmaterial without affecting the first material to leave a 3-D structuremade of only the first material.

Presented in method terms, various exemplary methods hereinautomatically electrostatically transfer a first material to an ITB, andalso automatically electrostatically transfer a second material to alocation of the ITB where the first material is located on the ITB. Eachlayer of the first and second materials is on a discrete area of the ITBand is in a pattern. Again, the second material dissolves in differentsolvents relative to solvents that dissolve the first material.

Such methods further automatically feed sheets of collapsible media to aplaten using a sheet feeder. Further, these methods automatically movethe platen toward the ITB to have a sheet of collapsible mediapositioned on the platen contact the ITB to transfer a layer of thefirst and second materials to the sheet of collapsible media. Afterthis, the methods automatically move the platen to a stabilizationstation to independently stabilize each layer of first and secondmaterials. Such methods automatically repeat the process of moving theplaten toward the ITB to have the sheet of collapsible media repeatedlycontact the ITB to successively form layers of the first and secondmaterials on the sheet of collapsible media, and after each time the ITBtransfers each of the layers to the sheet of collapsible media, thesemethods automatically repeat the process of the moving the platen to thestabilization station.

In later processing, these methods automatically feed the sheet ofcollapsible media having the layers thereon to a platform tosuccessively form a 3-D structure of freestanding stacks of the layers.Subsequently, these methods automatically apply heat and/or pressureand/or light to the 3-D structure to bond the freestanding stacks to oneanother through the sheets of collapsible media on the platform using abonding station. More specifically, the bonding process applies the heatand/or pressure and/or light after each time the platen transfers eachof the freestanding stacks to the platform to independently bond eachthe freestanding stack to any previously transferred ones of thefreestanding stacks of the 3-D structure on the platform.

Also, these methods can automatically feed the 3-D structure to asupport material removal station and apply a solvent there thatdissolves the second material without affecting the first material toleave the 3-D structure made of only the first material at the supportmaterial removal station.

These and other features are described in, or are apparent from, thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary systems and methods are described in detail below,with reference to the attached drawing figures, in which:

FIGS. 1-7 are schematic cross-section diagrams partially illustratingdevices herein;

FIG. 8 is an expanded schematic diagram illustrating devices herein;

FIGS. 9 and 10 are schematic cross-section diagrams partiallyillustrating devices herein;

FIG. 11 is an expanded schematic diagram illustrating devices herein;

FIG. 12 is a schematic cross-section diagram partially illustratingdevices herein;

FIG. 13 is an expanded schematic diagram illustrating devices herein;

FIGS. 14-21 are schematic cross-section diagrams partially illustratingdevices herein;

FIG. 22 is a flow diagram of various methods herein; and

FIGS. 23-25 are schematic cross-section diagrams illustrating devicesherein.

DETAILED DESCRIPTION

As mentioned above, electrostatic printing process are well-known meansof generating two-dimensional (2-D) digital images, and the methods anddevices herein use such processing for the production of 3-D items (for3-D printing). However, when performing 3-D printing using electrostaticprocesses (especially those that use an ITB); the thermal management isa challenge because of the high temperatures used to transfuse thematerial from the ITB to a platen, where the ITB is cooled beforereturning to the development device(s). Additionally, with 3-D printingthat uses electrostatic processes, the mechanical integrity of theprinted material may be compromised if it is very thin, and the transferprocess can impose stripping shear forces that can damage the material.

In order to address such issues, the devices and methods hereinrepeatedly electrostatically transfer the developed layers of build andsupport material from the ITB to a collapsible media (e.g., a “basestructure,” such as a polystyrene, etc.) to form a series of layers ofpolymer on the collapsible media as freestanding stacks of severalbuild/support layers. Such freestanding stacks are fused to one anotherthrough the sheets of collapsible media, to create a larger stack thatis eventually output for solvent application that removes the supportmaterial, leaving only the 3-D item of build material. In this way, the3-D structure is created consisting only of build material.

Thus, the systems and methods described herein center around using ahighly porous, collapsible substrate as a receiver/carrier of an imagedlayer of powders for 3-D printing. A layer of powder materialsconsisting of build and support materials is developed using anelectrostatic printing process. This powder layer is transferred onto aspecial collapsible substrate. Multiple powder layers can be accumulatedon the substrate. This substrate with the powder layers is then moved toa stacking/fusing station and fused with existing part, to increase thebuild volume by one predetermined thickness.

A typical process performed by the systems and methods hereindevelops/creates a powder layer using powders of build and supportmaterial. The build materials and support materials are developed usingtwo separate stations and form a uniform layer on a photoconductor or onan intermediate surface. The process then transfers the powder layer toa collapsible substrate. This transfer process can be an electrostatictransfer that draws the material from the development stations to theITB based on charge differences between the material and the ITB.

Further, such processing can optionally stabilize the powder layer onthe substrate. In such stabilization processes, the systems and methodsherein discharge the powder particles, for example, using pulse heating(flash, laser, IR etc.), to enable particle-particle weak bonding. Also,laser or flash light can be used to quickly but lightly sinter theparticles on the substrate to form a weakly connected layer that willnot be disturbed by subsequent electrostatic effects (such as“explosion” or blooming). The stabilization process leaves materialsthat are stable on the substrate, and that are even able to maintaintheir integrity standing alone as separate sheet.

Thus, the stabilization station can do many things to stabilize thetoner layer. For example, the stabilization station can discharge thetoner. The charges on the toner cause the toner to repel each other andcan cause disturbances. Therefore, the stabilization station can includedischarge methods and devices such as air ionization, corona devices,etc. Additionally, the stabilization station causes the build andsupport materials to weakly bond or sinter together, without causing toomuch damage to the collapsible substrate. In another example, thestabilization station can provide pulsed heating applied to the layer ofbuild and support material (with light pressure or no pressure). Thus,the stabilization station can provide flash light heating, laserheating, etc. Further, the stabilizer may be multiple separate units, ora composite device that performs many different stabilizing actions.

The process can be repeated as necessary in order to reach a desiredthickness. For example, the process can create a layer thickness ofabout 10× (where X represents a unitless measure, or representsconventional scales such as millimeters, microns, angstroms, etc.), andthrough repeated electrostatic printing of the layers, the systems andmethods can build a layer up to 1000×, or more. The layer thickness isoptimized for powder layer transfer and the subsequent stacking/fusingprocess. Too thin a layer will consume more substrate and will beinefficient thermally, but too thick a layer will cause transferproblems and subsequent thermal conduction problems, and part qualityproblems.

The systems and methods described herein stack the new groups of layers(with the collapsible substrate) on top of a partially built base part,fusing the new group of layers with the existing part through heat andpressure. For example, this can be done using radiant heating,convection heating, hot roll, hot plate, etc. Heat softens the thermalplastics and the pressure ensures solid bonding between the particles.

The systems and methods then repeat such processing until the entire 3-Dpart is fully formed. Post-processing can then be used to remove thesupport material and the substrate material within the support material.Based on the support material selection, a solvent based process istypically employed to remove the support material. To take advantage ofthis process and optimize the system performance, the collapsiblesubstrate materials are selected to be highly porous and collapsibleunder fusing conditions. The porosity of the collapsible substratematerials ensures minimal use of substrate materials for cost andperformance concerns. Collapsibility also enables solid build of thepart. The collapsible substrate is selected to be mechanically anddimensionally stable to go through the substrate handling part of thesystem and present an un-distorted powder layer to the stacking/fusingstation.

As shown, for example, in FIG. 1, exemplary three-dimensional (3-D)printers herein include, among other components, an intermediatetransfer belt 110 (ITB) supported on rollers 112, a first printingcomponent 116, a second printing component 114, and a platen 118 (whichcan be a surface or belt) adjacent the ITB 110. Further, a sheet feeder126 maintains sheets 108 of collapsible media. Such structures include astabilization station 120 positioned adjacent the platen 118. Alsoincluded is a platform 146, and a bonding station 122 is positioned toapply light, pressure, and/or heat. The structure can also include asupport material removal station 148.

As shown in FIG. 1, the first printing component 116 (which can be, forexample, a photoreceptor) is positioned to electrostatically transfer(by way of charge difference between the belt and the powder materialbeing transferred) a first material 104 (e.g., the build material, suchas a dry powder, polymer-wax material (e.g., charged 3-D toner)) to theITB 110, and a second printing component 114 (which can also be, forexample, a photoreceptor) is positioned to also electrostaticallytransfer a second material 105 (e.g., the support material, again suchas a dry powder, polymer-wax material (e.g., charged 3-D toner)) to alocation of the ITB 110 where the first material 104 is located on theITB 110.

The support material 105 dissolves in different solvents that do notaffect the build material 104 to allow the printed 3-D structure 104 tobe separated from the support material 105 used in the printing process.In the drawings, the combination of the build material 104 and thesupport material 105 is shown as element 102, and is referred to as adeveloped layer. The developed layer 102 of the build material 104 andthe support material 105 is on a discrete area of the ITB 110 and is ina pattern corresponding to the components of the 3-D structure in thatlayer (and its associated support elements), where the 3-D structure isbeing built, developed layer 102 by developed layer 102.

As shown in FIG. 1, the sheet feeder 126 is positioned to and does feedsheets 108 of collapsible media to the platen 118, using well-known,grabbers, rollers, nips, belts, etc. (all generally illustrated by item126). In this example, the platen 118 is a vacuum belt further movingthe sheet of collapsible media 108 and holding the sheet of collapsiblemedia 108 is place during the subsequent processing.

As shown by the vertical arrow in FIG. 2, the platen 118 moves (usingmotors, gears, pulleys, cables, guides, etc. (all generally illustratedby item 118)) toward the ITB 110 to have the sheet of collapsible media108 that is positioned on the platen 118 make contact with the ITB 110.The ITB 110 transfers one of the developed layer 102 of the buildmaterial 104 and the support material 105 to the sheet of collapsiblemedia 108 each time the platen 118 contacts the sheet of collapsiblemedia 108 with the ITB 110, to successively form developed layers 102 ofthe build material 104 and the support material 105 on the sheet ofcollapsible media 108.

Such build and support material are printed in a pattern on the ITB byeach separate development device 114, 116, and combine together in thedeveloped layers 102 to represent a specific pattern having apredetermined length. Thus, each of the developed layers 102 has aleading edge 134 oriented toward the processing direction in which theITB 110 is moving (represented by arrows next to the ITB 110) and atrailing edge 136 opposite the leading edge 134.

More specifically, as shown in FIG. 2, at the transfuse nip 130, theleading edge 134 of the developed layer 102 within the transfuse nip 130begins to be transferred to a corresponding location of the platen 118.Thus, in FIG. 2, the platen 118 moves to contact the developed layer 102on the ITB 110 at a location where the leading edge 134 of the developedlayer 102 is at the lowest location of the roller of the transfuse nip130. Thus, in this example, the trailing edge 136 of the developed layer102 has not yet reached the transfuse nip 130 and has not, therefore,yet been transferred to the platen 118.

As shown in FIG. 3, the platen 118 moves synchronously with the ITB 110(moves at the same speed and the same direction as the ITB 110) eitherby moving or rotating the platen vacuum belt, to allow the developedlayers 102 to transfer cleanly to the platen 118, without smearing. InFIG. 3, the trailing edge 136 of the developed layer 102 is the onlyportion that has not yet reached the transfuse nip 130 and has not,therefore, been transferred to the platen 118 or partially formed part106. Then, as the ITB 110 moves in the processing direction, the platen118 moves at the same speed and in the same direction as the ITB 110,until the trailing edge 136 of the developed layer 102 reaches thebottom of the roller of the transfuse nip 130, at which point the platen118 moves away from the ITB 110 and over to the stabilization station120, as shown in FIG. 4. The stabilization station 120 can be anon-contact (e.g., pulse heater (flash, laser, IR, etc.), to enableparticle-particle weak bonding, or a pressure heater, such as a fuserroller.

For example, the stabilizer station 120 can comprise a highlycontrollable resistive or light device that only provides heat for alimited time and to a limited depth, so as to only affect the topdeveloped layer 102, without affecting underlying developed layers 102or the collapsible media 108. Such highly controllable resistive orlight devices can include, for example, a laser or infrared light sourcethat flashes for a limited exposure time. Therefore, as noted above, thestabilizer station 120 can do many things to stabilize the toner layer.For example, the stabilizer station 120 can discharge the toner, and caninclude discharge methods and devices such as air ionization, coronadevices, etc. Additionally, the stabilizer station 120 causes the buildand support materials to weakly bond or sinter together, without causingtoo much damage to the collapsible substrate 108. In another example,the stabilizer station 120 can provide pulsed heating, flash lightheating, laser heating, etc. Therefore, the stabilizer station 120 maybe multiple separate units, or a composite device that performs manydifferent stabilizing actions.

As shown in FIG. 5, the stabilizer station 120 can briefly apply heat toonly the top developed layer 102, without affecting underlying developedlayers 102 or the collapsible media 108. Therefore, the stabilizerstation 120 can be controlled to not physically contact the topdeveloped layer, but to only briefly supply heat to the top developedlayer 102 to provide a minimum amount of melting so as to promoteparticle-particle weak bonding only within the top developed layer 102(which will also reduce the charge of the top developed layer 102) andto bond the top developed layer to the immediately adjacent underlyingdeveloped layer 102 or to the collapsible media 108.

The platen 118 can move to the stabilization station 120 after each timethe ITB 110 transfers each of the developed layers 102 to the sheet ofcollapsible media 108 to independently stabilize each of the developedlayers 102 immediately after disposition to the collapsible media 108.In other alternatives, the platen 118 may only move to the stabilizationstation 120 after a specific number (e.g., 2, 3, 4, etc.) of thedeveloped layers 102 have been placed on the sheet of collapsible media108 to allow multiple developed layers 102 to be simultaneouslystabilized.

Thus, the processing in FIGS. 2-5 is repeated to deposit and stabilizemultiple developed layers 102 on the sheet of collapsible media 108, asshown in FIG. 6. As the stack 106 of the developed layers 102 grows,additional developed layers 102 are formed on top of the stack 106, asshown in FIG. 6, and such additional developed layers 102 are stabilizedby the stabilization station 120, as shown in FIG. 7, to fuse all thedevelop layers 102 within the stack 106 together.

FIG. 8 is an expanded diagram showing how the developed layers 102 maycontain some of the build material 104 and some of the support material105, and how the lowest developed layer 102 is joined to the sheet ofcollapsible media 108, and how each successive developed layer 102contacts and is joined to the immediately preceding adjacent developedlayer 102 that is below (e.g., is between the layer 102 and the sheet ofcollapsible media 108) to form a stack 106 of developed layers 102 onthe single sheet of collapsible media 108.

As noted above, the particles of build materials 104 and supportmaterial 105 within the developed layer 102 (shown as particles (notdrawn to scale) in FIG. 8, using identification number 102) are chargedparticles of powder, and FIG. 8 shows these items as negatively chargedparticles (or they could be positively charged). As is understood bythose ordinarily skilled in the art, the printing components 114, 116provide the charge to the particles 102 in order to have such particleselectrostatically transfer to the ITB 110. A charge generator 132 can beused to create an opposite charge 152 (in this case a positive charge)on the opposite side of the platen 118, and this opposite charge 152draws the charged particles 102 from the ITB 110 to the top of the stack106.

However, at some point, the height of the stack 106 will make thedistance between the charged (build and support) particles 102 greaterthan the ability of the opposite charges 152 to attract the chargedparticles 102, as shown in FIG. 8 (and this height will vary, dependingupon the strength of the various charges). When the stack 106 heightreaches this point (or before), processing then transfers the sheet ofcollapsible media 108 and the stack 106 to the platform 146, as shown inFIG. 9.

Thus, as shown in FIG. 9, the platform 146 is positioned to receive,from the platen 142, the freestanding stack 106. Also, the bondingstation 122 is configured to apply heat and/or pressure and/or light tothe 3-D structure to bond the developed layers 102 in the freestandingstack 106 to one another through the sheets of collapsible media on theplatform 146 as shown in FIGS. 10-13. The selective use of heaters,lights, and other components 122 of the bonding station will varydepending upon the chemical makeup of the developed layers 102. Eachfreestanding stack 106 of collapsible media 108 and developed layers canbe individually bonded by the bonding station as shown in FIG. 10-13immediately after the freestanding stack 106 is transferred to theplatform 146 (or to the top existing freestanding stack 106 ofpreviously bonded freestanding stacks 106 on the platform 146), orprocessing can proceed to bond the freestanding stacks 106 in groups (2at a time, 3 at a time, etc.), depending upon the height of thefreestanding stacks 106, their chemical makeup, the temperature andpressure exerted by the bonding station 122, etc.

FIG. 11 is an expanded view of the action of the bonding station shownin FIG. 10, which can include a radiant heater, convection heater, hotpressure roll, hot pressure plate, etc., to perform bonding. In theexample shown in shown in FIGS. 10 and 11, the bonding station 122 has aheated pressure roller and the platform 146 moves synchronously (asindicated by the arrows in the drawings) as the roller rotates, heatingand pressing to fuse the developed layers 102 to one another (usingcontrolled temperature and pressure to avoid distorting the pattern ofthe build and support materials within each of the developed layers102). This synchronous movement causes the pattern of support and buildmaterials (102) that is printed by the development devices 116, 114 tobe fused and bonded, without distortion or smearing.

FIG. 13 is an expanded view of the action of the bonding station 122shown in FIG. 12. As shown in FIGS. 12 and 13, after the platform 146has moved past the bonding station, the thickness of the sheet ofcollapsible media 108 has been substantially reduced (e.g., by more than10 times, 100 times, 1000 times, etc.) This can be seen by comparing thethickness of the upper sheet of collapsible media 108 in FIGS. 11 and 13(not drawn to scale).

Further, the developed layers 102 on either side of each of the sheetsof collapsible media 108 bond through the sheet of collapsible media108, as shown in FIG. 13 (where the upper sheet of collapsible media 108has a somewhat broken appearance after bonding) because very little ofthe collapsible media 108 may remain after bonding. Bonding of thedeveloped layers 102 through the sheet of collapsible media 108 occursbecause the sheet of collapsible media 108 is very porous (e.g.,containing more than 65%, 80%, 95%, etc. pores) and because the sheet ofcollapsible media 108 has been reduced in thickness by a large measure(e.g., the thickness of the sheet of collapsible media 108 can bereduced by orders of magnitude (e.g., reduced by ½, ⅕, 1/10, 1/100,1/1000, etc., the original thickness) by the action of the bondingstation 122 shown in FIGS. 10-13). In some situations portions (or all)of the sheet of collapsible media 108 is vaporized or merged into thesurrounding layers by the action of the bonding station, essentiallyeliminating the sheets of collapsible media 108 from the structure forpurposes of appearance or structural strength.

The collapsible substrate 108 can be made of aconductive/semi-conductive material to ease the electrostatic powderlayer transfer and enable multi-layer build up. The collapsiblesubstrate material 108, when molten, can optionally be selected to becompatible with (have similar material characteristics of) the buildmaterial 104, to ensure the part strength. Furthermore, the collapsiblesubstrate material 108, when molten, can optionally be selected to beincompatible with (have different material characteristics relative to)the support material 105 to allow the support material 105 to be easilyremoved/dissolved from both the build material 104 and the collapsiblesubstrate material 108.

As the collapsible substrate 108 is collapsing under fusing conditionsapplied by the fusing station 122, the collapsible substrate 108 may nothold the shape of a layer of thin film. Due to the gain/cell nature ofthe porous structure, when melted, the collapsible substrate 108 canform into discontinuous islands (as shown in FIG. 13, where the uppersheet of collapsible media 108 has a somewhat broken appearance afterbonding).

In addition, due to intentional material mismatch of the supportmaterial 105, the droplet formation of the collapsible substrate 108 canbe encouraged. In other situations, by selecting the material of thecollapsible substrate 108 to be incompatible build material 104 (butpotentially compatible with the support material 105), the collapsedsubstrate material 108 can transform into dispersed small droplets thatmigrate to the support material 105 during the bonding process. Thisjoins the now reduced material of the collapsible substrate 108 with thesupport material, and thereby enables easy removal of the substratematerial 108 within the support material 105 in the final solvent.Therefore, depending upon material choice, the substrate material 108can remain in the final structure within the build material 104 withoutvisually or structurally affecting the build material 104, or can beremoved with the support material 105 if the build material 104 isselected to repel the substrate material 108 so that it migrates to thesupport material 105 during bonding.

Examples the collapsible material 108 are both open foam and closed foamand a foam material made from polystyrene with porosity in the range of95%-98%. The collapsible material 108 can also be a highly porous foamof the build material 104 to allow the collapsible material 108 tobecome one with the build material during bonding.

In one example, a collapsible material 108 of around 100-200 X (where Xagain is an arbitrary unit of measure) thickness is mechanicallysufficient to perform the processing described herein. With a 98%porosity, the collapsible substrate 108 is transformed to a mere 2-4 Xthin layer of discontinuous islands (or droplets) after fusing (e.g., a100 times reduction ( 1/100 of the original thickness)). Additionally,if an exemplary 200 times worth of build and support material isaccumulated on each collapsible substrate 108 before stacking andfusing, the ratio of 3-D printing material to collapsible substratematerial 108 is 100:1 or 100:2, demonstrating that the amount ofcollapsible substrate material 108 remaining after bonding isinsignificant in structure or appearance. The molten substrate material108 may not form a continuous film, and instead may break up into smalldroplets due to surface tension. Exemplary small droplets of polystyrenesparsely dispersed in a polymer support material 105 does not affectappearance or strength. Even if the build material 104 is incompatiblewith polystyrene, the presence of such a small ratio of polystyrenedroplets does not affect the strength of the build part.

Other examples of materials that can be used as the collapsiblesubstrate 108 are high performance thermal plastic foams: thesematerials can be synthetic polymers, such as aliphatic or semi-aromaticpolyamides with generally >95% porosity. Therefore, the base chemical ofthe build material 104 can be the same as that of the foam substrate108. This can ensure the complete compatibility between the build andthe substrate 108 and guaranties build integrity. In addition, thecollapsible substrate 108 can also be selected to change the propertycharacteristics of the 3-D part produced in many different ways, forexample: electrical (conductivity), thermal, color, etc.

Indeed, the action of the bonding station 122 can reduce the thicknessof the sheet of collapsible media 108 below the size that is visible tothe unaided human eye, and the connection of the developed layer 102through the portion of the sheet of collapsible media 108 that remains(if any) allows such developed layers 102 that are separated by a sheetof collapsible media 108 to be bonded with the same strength as if thesheet of collapsible media 108 was not present. This allows the sheet ofcollapsible media 108 (or portions thereof) to remain in the finalstructure, without affecting the appearance or strength of the finalstructure.

The bonding station can also perform light-based curing, as shown by thewavy lines in FIGS. 10 and 13. As with the other bonding, light-basedcuring can be performed on one freestanding stack 106 at a time, or thefreestanding stacks 106 can be subjected to light-based curing inbatches. Further, the light-based curing can be performed by the bondingstation 122 at different times from the heat and pressure-based bonding.Also, the bonding and fusing functions can be performed by separatestations positioned in different locations, and bonding station 122shown is only example.

The build material 104 and the support material 105 can contain UVcurable toners. The bonding station 122 bonds such materials by heatingthe materials to a temperature between their glass transitiontemperature and their melting temperature, and then applies UV light tocross-link the polymers within the materials, thereby creating a rigidstructure. Those ordinarily skilled in the art would understand thatother build and support materials would utilize other bonding and curingprocessing and bonding and curing components, and that the foregoing ispresented only as one limited example; and the devices and methodsherein are applicable to all such bonding methods and components,whether currently known or developed in the future.

As shown in FIG. 14, processing continues to create new freestandingstacks 106, that are repeatedly transferred to the platform 146, andthis repeated processing bonds the developed layers 102 in each of thefreestanding stacks 106 to each other, and to any previously transferredfreestanding stacks 106 of the 3-D structure on the platform 146, tosuccessively form a 3-D structure of freestanding stacks 106 as shown inFIG. 15. Note that FIG. 15 illustrates an overlay showing portions ofsupport material 105 and build material 104 within the accumulation offreestanding stacks 106. Such may or may not be visible, and is onlyillustrated to show one exemplary way in which such build and supportmaterials may be arranged.

The 3-D structure of freestanding stacks 106 shown in FIG. 15 can beoutput to allow manual removal of the support material 105 using anexternal solvent bath; or processing can proceed as shown in FIG. 16-18.More specifically, in FIG. 16, the support material removal station 148is positioned to apply a solvent 156 that dissolves the support material105 without affecting the build material 104. Again, as noted above, thesolvent utilized will depend upon the chemical makeup of the buildmaterial 104 and the support material 105. FIG. 17 illustrates theprocessing where about half of the support material 105 remains, and aportion of the build material 104 protrudes from the remaining stack ofsupport material 105. FIG. 18 illustrates processing after the supportmaterial removal station 148 has applied sufficient solvent 156 todissolve all the support material 105, leaving only the build material104 remaining, which leave a completed 3-D structure made of only thebuild material 104.

FIGS. 19 and 20 illustrate an alternative 3-D electrostatic printingstructure herein which includes a planar transfuse station 138 in placeof the transfuse nip 130 shown in FIG. 2. As shown in FIG. 19, theplanar transfuse station 138 is a planar portion of the ITB 110 that isbetween rollers 112 and is parallel to the platen 118. As shown in FIG.20, with this structure, when the platen 118 moves to contact the planartransfuse station 138, all of the developed layer 102 is transferredsimultaneously to the platen 118 or partially formed stack 106, avoidingthe rolling transfuses process shown in FIGS. 2 and 3.

Similarly, as shown in FIG. 21, a drum 178 could be used in place of theITB 110, with all other components operating as described herein. Thus,the drum 178 could be an intermediate transfer surface receivingmaterial from development stations 114, 116, as described above, orcould be a photoreceptor and operate as the photoreceptor 256 describedbelow operates, by maintaining a latent image of charge and receivingmaterials from development devices 254.

FIG. 22 is flowchart illustrating exemplary methods herein. In item 170,these various exemplary methods automatically electrostatically transferfirst and second materials to an ITB. In item 170, the second materialis transferred on the first material (e.g., to a location of the ITBwhere the first material is already located on the ITB). Again, thesecond material dissolves in different solvents relative to solventsthat dissolve the first material. The layer of the first and secondmaterials is on a discrete area of the ITB and is in a pattern.

In item 172, such methods further automatically feed sheets ofcollapsible media to a platen using a sheet feeder. Further, in item174, these methods automatically move the platen toward the ITB to havea sheet of collapsible media positioned on the platen contact the ITB totransfer a layer of the first and second materials to the sheet ofcollapsible media.

After this, in item 176, the methods automatically move the platen to astabilization station to stabilize the developed layer and join thedeveloped layer to the sheet of collapsible media. As shown by the arrowfrom item 176 to item 174, such methods automatically repeat the processof moving the platen toward the ITB to have the sheet of collapsiblemedia repeatedly contact the ITB to successively form layers of thefirst and second materials on the sheet of collapsible media, and aftereach time the ITB transfers each of the layers to the sheet ofcollapsible media, these methods automatically repeat the process of themoving the platen to the stabilization station to independentlystabilize and successively join each new developed layers to thepreviously formed developed layer(s) on the sheet of collapsible media.

Then, in item 178, these methods automatically feed the freestandingstack to a platform to successively form a 3D structure of freestandingstacks of the layers. In item 180, these methods automatically applyheat and/or pressure and/or light to the 3-D structure to bond thefreestanding stacks to one another through the sheets of collapsiblemedia on the platform using a bonding station. More specifically, thebonding process in item 180 applies the heat and/or pressure and/orlight after each time the platen transfers each of the freestandingstacks to the platform to independently bond each the freestanding stackto any previously transferred ones of the freestanding stacks of the 3-Dstructure on the platform.

Also, in item 182, these methods can automatically feed the 3D structureto a support material removal station and apply a solvent there thatdissolves the second material without affecting the first material toleave the 3D structure made of only the first material at the supportmaterial removal station.

FIG. 23 illustrates many components of 3-D printer structures 204herein. The 3-D printing device 204 includes a controller/tangibleprocessor 224 and a communications port (input/output) 214 operativelyconnected to the tangible processor 224 and to a computerized networkexternal to the printing device 204. Also, the printing device 204 caninclude at least one accessory functional component, such as a graphicaluser interface (GUI) assembly 212. The user may receive messages,instructions, and menu options from, and enter instructions through, thegraphical user interface or control panel 212.

The input/output device 214 is used for communications to and from the3-D printing device 204 and comprises a wired device or wireless device(of any form, whether currently known or developed in the future). Thetangible processor 224 controls the various actions of the printingdevice 204. A non-transitory, tangible, computer storage medium device210 (which can be optical, magnetic, capacitor based, etc., and isdifferent from a transitory signal) is readable by the tangibleprocessor 224 and stores instructions that the tangible processor 224executes to allow the computerized device to perform its variousfunctions, such as those described herein. Thus, as shown in FIG. 23, abody housing has one or more functional components that operate on powersupplied from an alternating current (AC) source 220 by the power supply218. The power supply 218 can comprise a common power conversion unit,power storage element (e.g., a battery, etc), etc.

The 3-D printing device 204 includes at least one marking device(printing engine(s)) 240 that deposits successive layers of build andsupport material on a platen as described above, and are operativelyconnected to a specialized image processor 224 (that is different than ageneral purpose computer because it is specialized for processing imagedata). Also, the printing device 204 can include at least one accessoryfunctional component (such as a scanner 232) that also operates on thepower supplied from the external power source 220 (through the powersupply 218).

The one or more printing engines 240 are intended to illustrate anymarking device that applies build and support materials (toner, etc.)whether currently known or developed in the future and can include, forexample, devices that use an intermediate transfer belt 110 (as shown inFIG. 24).

Thus, as shown in FIG. 24, each of the printing engine(s) 240 shown inFIG. 23 can utilize one or more potentially different (e.g., differentcolor, different material, etc.) build material development stations116, one or more potentially different (e.g., different color, differentmaterial, etc.) support material development stations 114, etc. Thedevelopment stations 114, 116 can be any form of development station,whether currently known or developed in the future, such as individualelectrostatic marking stations, individual inkjet stations, individualdry ink stations, etc. Each of the development stations 114, 116transfers a pattern of material to the same location of the intermediatetransfer belt 110 in sequence during a single belt rotation (potentiallyindependently of a condition of the intermediate transfer belt 110)thereby, reducing the number of passes the intermediate transfer belt110 must make before a full and complete image is transferred to theintermediate transfer belt 110.

One exemplary individual electrostatic development station 114, 116 isshown in FIG. 25 positioned adjacent to (or potentially in contact with)intermediate transfer belt 110. Each of the individual electrostaticdevelopment stations 114, 116 includes its own charging station 258 thatcreates a uniform charge on an internal photoreceptor 256, an internalexposure device 260 that patterns the uniform charge into a patternedcharge on the photoreceptor, and an internal development device 254 thattransfers build or support material to the photoreceptor 256. Thepattern of build or support material is then transferred from thephotoreceptor 256 to the intermediate transfer belt 110 and eventuallyfrom the intermediate transfer belt to the sheet of collapsible media108. While FIG. 24 illustrates five development stations adjacent or incontact with a rotating belt (110), as would be understood by thoseordinarily skilled in the art, such devices could use any number ofmarking stations (e.g., 2, 3, 5, 8, 11, etc.).

While some exemplary structures are illustrated in the attacheddrawings, those ordinarily skilled in the art would understand that thedrawings are simplified schematic illustrations and that the claimspresented below encompass many more features that are not illustrated(or potentially many less) but that are commonly utilized with suchdevices and systems. Therefore, Applicants do not intend for the claimspresented below to be limited by the attached drawings, but instead theattached drawings are merely provided to illustrate a few ways in whichthe claimed features can be implemented.

As shown in U.S. Pat. No. 8,488,994, an additive manufacturing systemfor printing a 3-D part using electrophotography is known. The systemincludes a photoconductor component having a surface, and a developmentstation, where the development station is configured to developed layersof a material on the surface of the photoconductor component. The systemalso includes a transfer medium configured to receive the developedlayers from the surface of the rotatable photoconductor component, and aplaten configured to receive the developed layers from the transfercomponent in a layer-by-layer manner to print the 3-D part from at leasta portion of the received layers.

With respect to UV curable toners, as disclosed in U.S. Pat. No.7,250,238 it is known to provide a UV curable toner composition, as aremethods of utilizing the UV curable toner compositions in printingprocesses. U.S. Pat. No. 7,250,238 discloses various toner emulsionaggregation processes that permit the generation of toners that inembodiments can be cured, that is by the exposure to UV radiation, suchas UV light of has about 100 nm to about 400 nm. In U.S. Pat. No.7,250,238, the toner compositions produced can be utilized in variousprinting applications such as temperature sensitive packaging and theproduction of foil seals. In U.S. Pat. No. 7,250,238 embodiments relateto a UV curable toner composition comprised of an optional colorant, anoptional wax, a polymer generated from styrene, and acrylate selectedfrom the group consisting of butyl acrylate, carboxyethyl acrylate, anda UV light curable acrylate oligomer. Additionally, these aspects relateto a toner composition comprised of a colorant such as a pigment, anoptional wax, and a polymer generated from a UV curable cycloaliphaticepoxide.

Moreover, U.S. Pat. No. 7,250,238 discloses a method of forming a UVcurable toner composition comprising mixing a latex containing a polymerformed from styrene, butyl acrylate, a carboxymethyl acrylate, and a UVcurable acrylate with a colorant and wax; adding flocculant to thismixture to optionally induce aggregation and form toner precursorparticles dispersed in a second mixture; heating the toner precursorparticles to a temperature equal to or higher than the glass transitiontemperature (Tg) of the polymer to form toner particles; optionallywashing the toner particles; and optionally drying the toner particles.A further aspect relates to the toner particles produced by this method.

Many computerized devices are discussed above. Computerized devices thatinclude chip-based central processing units (CPU's), input/outputdevices (including graphic user interfaces (GUI), memories, comparators,tangible processors, etc.) are well-known and readily available devicesproduced by manufacturers such as Dell Computers, Round Rock Tex., USAand Apple Computer Co., Cupertino Calif., USA. Such computerized devicescommonly include input/output devices, power supplies, tangibleprocessors, electronic storage memories, wiring, etc., the details ofwhich are omitted herefrom to allow the reader to focus on the salientaspects of the systems and methods described herein. Similarly,printers, copiers, scanners and other similar peripheral equipment areavailable from Xerox Corporation, Norwalk, Con., USA and the details ofsuch devices are not discussed herein for purposes of brevity and readerfocus.

The terms printer or printing device as used herein encompasses anyapparatus, such as a digital copier, bookmaking machine, facsimilemachine, multi-function machine, etc., which performs a print outputtingfunction for any purpose. The details of printers, printing engines,etc., are well-known and are not described in detail herein to keep thisdisclosure focused on the salient features presented. The systems andmethods herein can encompass systems and methods that print in color,monochrome, or handle color or monochrome image data. All foregoingsystems and methods are specifically applicable to electrostatographicand/or xerographic machines and/or processes.

For the purposes of this invention, the term fixing means the drying,hardening, polymerization, crosslinking, binding, or addition reactionor other reaction of the coating. In addition, terms such as “right”,“left”, “vertical”, “horizontal”, “top”, “bottom”, “upper”, “lower”,“under”, “below”, “underlying”, “over”, “overlying”, “parallel”,“perpendicular”, etc., used herein are understood to be relativelocations as they are oriented and illustrated in the drawings (unlessotherwise indicated). Terms such as “touching”, “on”, “in directcontact”, “abutting”, “directly adjacent to”, etc., mean that at leastone element physically contacts another element (without other elementsseparating the described elements). Further, the terms automated orautomatically mean that once a process is started (by a machine or auser), one or more machines perform the process without further inputfrom any user. In the drawings herein, the same identification numeralidentifies the same or similar item.

It will be appreciated that the above-disclosed and other features andfunctions, or alternatives thereof, may be desirably combined into manyother different systems or applications. Various presently unforeseen orunanticipated alternatives, modifications, variations, or improvementstherein may be subsequently made by those skilled in the art which arealso intended to be encompassed by the following claims. Unlessspecifically defined in a specific claim itself, steps or components ofthe systems and methods herein cannot be implied or imported from anyabove example as limitations to any particular order, number, position,size, shape, angle, color, or material.

What is claimed is:
 1. A three-dimensional (3-D) printer comprising: anintermediate transfer surface having a layer of a first material and asecond material, said layer of said first material and said secondmaterial is on a discrete area of said intermediate transfer surface andis in a pattern; a platen moving relative to said intermediate transfersurface; a sheet feeder positioned to feed sheets of collapsible mediato said platen, said platen repeatedly moves toward said intermediatetransfer surface to have a sheet of collapsible media positioned on saidplaten repeatedly contact said intermediate transfer surface, saidintermediate transfer surface transfers said layer of said firstmaterial and said second material to said sheet of collapsible mediaeach time said platen contacts said sheet of collapsible media with saidintermediate transfer surface to successively form a freestanding stackof layers of said first material and said second material on said sheetof collapsible media; a platform positioned to receive, from saidplaten, said freestanding stack to successively form a 3-D structure offreestanding stacks of said layers of said first material and saidsecond material on said sheet of collapsible media; and a bondingstation positioned to apply heat, pressure, and/or light to said 3-Dstructure to bond said freestanding stacks to one another through saidsheets of collapsible media on said platform.
 2. The 3-D printeraccording to claim 1, said collapsible media comprises a porous materialhaving a density relatively lower than said layer of said first materialand said second material.
 3. The 3-D printer according to claim 1, saidcollapsible media comprises a polystyrene or plastic material having aporosity above 95%.
 4. The 3-D printer according to claim 1, saidbonding station applies said light and/or said heat after each time saidplaten transfers each of said freestanding stacks to said platform toindependently bond each said freestanding stack to any previouslytransferred ones of said freestanding stacks of said 3-D structure onsaid platform.
 5. The 3-D printer according to claim 1, furthercomprising a support material removal station positioned to receive said3-D structure from said platform, said support material removal stationapplies a solvent that dissolves said second material without affectingsaid first material to leave said 3-D structure made of only said firstmaterial.
 6. A three-dimensional (3-D) printer comprising: anintermediate transfer belt (ITB); a first photoreceptor positioned toelectrostatically transfer a first material to said ITB; a secondphotoreceptor positioned to electrostatically transfer a second materialto a location of said ITB where said first material is located on saidITB, said second material dissolves in different solvents relative tosolvents that dissolve said first material; a platen moving relative tosaid ITB; a sheet feeder positioned to feed sheets of collapsible mediato said platen, said platen repeatedly moves toward said ITB to have asheet of collapsible media positioned on said platen repeatedly contactsaid ITB, said ITB electrostatically transfers a layer of said firstmaterial and said second material to said sheet of collapsible mediaeach time said platen contacts said sheet of collapsible media with saidITB to successively form layers of said first material and said secondmaterial on said sheet of collapsible media, said layer of said firstmaterial and said second material is on a discrete area of said ITB andis in a pattern; a stabilization station adjacent said platen, saidplaten moves to said stabilization station after each time said ITBtransfers each of said layers to said sheet of collapsible media toindependently stabilize each of said layers of said first material andsaid second material on said sheet of collapsible media; a platformpositioned to receive, from said platen, said freestanding stack tosuccessively form a 3-D structure of freestanding stacks of said layersof said first material and said second material on said sheet ofcollapsible media; and a bonding station positioned to apply heat,pressure, and/or light to said 3-D structure to bond said freestandingstacks to one another through said sheets of collapsible media on saidplatform.
 7. The 3-D printer according to claim 6, said collapsiblemedia comprises a porous material having a density relatively lower thansaid layer of said first material and said second material.
 8. The 3-Dprinter according to claim 6, said collapsible media comprises apolystyrene or plastic material having a porosity above 95%.
 9. The 3-Dprinter according to claim 6, said bonding station applies said lightand/or said heat after each time said platen transfers each of saidfreestanding stacks to said platform to independently bond each saidfreestanding stack to any previously transferred ones of saidfreestanding stacks of said 3-D structure on said platform.
 10. The 3-Dprinter according to claim 6, further comprising a support materialremoval station positioned to receive said 3-D structure from saidplatform, said support material removal station applies a solvent thatdissolves said second material without affecting said first material toleave said 3-D structure made of only said first material.